1. Field of the Invention
The present invention relates to a pretensioner device which is used in a seat belt device for a vehicle, and which, at the time of a rapid deceleration of a vehicle such as a collision or the like, tenses a webbing for restraining a vehicle occupant, in the direction of restraining the vehicle occupant.
The present invention also relates to a three-point seat belt device equipped with the pretensioner device.
2. Description of the Related Art
Among seat belt devices for vehicles, there are three-point seat belt devices using a continuous webbing.
In this type of seat belt device, one end portion of the webbing is anchored to a take-up device (retractor), the intermediate portion of the webbing passes through a through-anchor fixed to the upper portion of the center pillar, and the other end portion of the webbing is anchored on an anchor plate. A tongue plate is disposed at the intermediate portion of the webbing between the anchor plate and the through-anchor. By anchoring the tongue plate in a buckle device disposed at the side of a seat, the webbing is pulled out from the retractor and applied to the vehicle occupant.
In this state, the shoulder webbing, which is from the through-anchor to the tongue plate (the buckle device), restrains the upper body of the vehicle occupant, whereas the lap webbing, which is from the tongue plate to the anchor plate, restrains the waist portion of the vehicle occupant.
Among such seat belt devices, there are those which are provided with a pretensioner device for tensing, in the direction of restraining the vehicle occupant, the webbing at the time of a rapid deceleration of the vehicle, such as at the time of a collision or the like. The seat belt device has a shoulder pretensioner device which is generally provided at the retractor and which rotates the take-up shaft of the retractor in a webbing take-up direction at the time of a rapid deceleration of the vehicle, so as to tense the webbing. Moreover, structures are known which, in order to improve the vehicle occupant restraining performance at the time of a rapid deceleration of the vehicle, have, in addition to the shoulder pretensioner device, a lap pretensioner device which pulls the buckle device or the anchor plate in toward the vehicle body so as to tense the webbing.
A structure equipped with a piston which is connected to the buckle device or the like via a wire; a cylinder; a base cartridge; and a gas generating means which is provided at the base cartridge and can supply gas to the cylinder, is known as a lap pretensioner device. The cylinder is cylindrical. The piston is disposed at one end side of the cylinder, and is accommodated within the cylinder so as to be movable toward the other end side of the cylinder. The base cartridge is a member which is connected to the one end side of the cylinder and bends back the intermediate portion of the wire toward the cylinder, and the bent-back intermediate portion of the wire is inserted through the base cartridge.
In this way, when the gas generating means is operated at the time of a rapid deceleration of the vehicle, gas is supplied to the interior of the cylinder. Due to the pressure of the supplied gas, the piston moves within the cylinder along the axial direction thereof toward the other end side, and the buckle device is pulled in toward the vehicle body.
However, in such a lap pretensioner device, because the piston moves rectilinearly within the cylinder and pulls in the wire, there is the problem that the outer shape of the lap pretensioner device (the space for mounting the lap pretensioner device in the vehicle) is large and the mountability of the lap pretensioner device into the vehicle is poor. Moreover, the lap pretensioner device must be mounted to the vehicle body separately from the retractor. The mountability of the overall seat belt device into the vehicle is poor, which results in higher costs.
Moreover, a lap pretensioner device, which has the above-described structure in which the buckle device or the anchor plate is pulled in, is mounted to the floor panel of the vehicle. Therefore, the need arises for special measures for improving the rigidity of the floor panel and the like, and there is the problem that this greatly affects the body structure (design). For example, reinforcing of the floor panel is a cause of preventing lightening of the weight of the vehicle.
In view of the aforementioned, an object of the present invention is to provide a pretensioner device which is compact and has improved mountability into a vehicle.
Another object of the present invention is to provide a seat belt device which is equipped with the above pretensioner device, and with which the space for mounting the seat belt device into a vehicle can be reduced while the ability thereof to restrain the vehicle occupant is maintained.
In order to achieve the above-described first object, a pretensioner device relating to a first aspect of the present invention is provided at another end portion of a webbing for restraining a vehicle occupant whose one end portion is anchored to a retractor so as to be freely taken-up and pulled-out, and the pretensioner device tenses the webbing for restraining a vehicle occupant in a direction of restraining a vehicle occupant at a time of rapid deceleration of a vehicle. The pretensioner device comprises: a webbing for tensing which is connected to the other end portion of the webbing for restraining a vehicle occupant and whose width is narrower than a width of the webbing for restraining a vehicle occupant; a spool at which a free end portion of the webbing for tensing is anchored, and which rotates and can take-up the webbing for tensing; and a driving device rotating the spool in a direction of taking-up the webbing for tensing at a time of rapid deceleration of the vehicle.
In the pretensioner device of the present invention, the free end portion of the webbing for tensing, which is connected to the other end portion of the webbing for restraining a vehicle occupant, is anchored on the spool. The other end portion of the webbing for restraining a vehicle occupant, which usually can be freely pulled-out and taken-up by the retractor, is fixed and held via the webbing for tensing.
Note that, in a structure in which the webbing for tensing is wound on the spool in an initial state, it is preferable to provide a restricting device which restricts rotation of the spool in the direction of pulling-out the webbing for tensing.
At the time of a rapid deceleration of the vehicle, the driving device operates, and the driving device rotates the spool in the direction of taking-up the webbing for tensing. The webbing for tensing is thereby taken up onto the spool, and tenses the webbing for restraining a vehicle occupant in the direction of restraining the vehicle occupant.
Here, because the pretensioner device tenses the webbing for restraining a vehicle occupant by taking-up the webbing for tensing, the longitudinal dimension of the pretensioner device is small as compared with a structure in which a wire connected to a piston is pulled in rectilinearly as in the conventional art. Further, because the webbing for tensing has a more narrow width than the width of the webbing for restraining a vehicle occupant, the widthwise dimension can be prevented from becoming large, and the pretensioner device can be made more compact on the whole.
Because the pretensioner device is structured to take-up the webbing for tensing which is connected to the other end portion of the webbing for restraining a vehicle occupant, there is no need to mount the pretensioner device to the floor panel of a vehicle. Accordingly, the range over which the pretensioner device can be mounted in a vehicle is broadened, and the mountability improves. Further, for example, if the pretensioner device is structured so as to be mounted to the lower portion of the center pillar together with the retractor, there are few effects on the body structure.
In this way, the pretensioner device of the present invention is compact, and the mountability thereof to a vehicle is improved.
There are cases in which the pretensioner device relating to the present invention has a base member which is formed in a block shape, and accommodates the spool further toward one side of the base member than a central portion in a widthwise direction of the base member such that a rotational axial direction of the spool and the widthwise direction of the base member coincide, and the driving device is assembled to another side of the base member in the widthwise direction.
In a pretensioner device having such a base member, the spool is accommodated (disposed) further toward one side than a central portion in the widthwise direction of the base member. In addition, the driving device is built into the side of the base member opposite the side at which the spool is provided. As a result, the driving device is positioned at one end side in the axial direction of the spool, and the pretensioner device can be made more compact on the whole.
In particular, in a structure in which the diameter of the spool is made to be large and the amount of rotation of the spool with respect to a predetermined take-up amount of the webbing for tensing (the change in the dimension in the radial direction of the spool before and after taking-up of the webbing for tensing) is kept low, it suffices for the range of operation of the driving device (the range over which the driving device rotates the spool) to be small (the dimension of the driving device with respect to the spool is relatively small). As a result, the pretensioner device can be made even more compact.
When the pretensioner device relating to the present invention has the above-described base member, there are cases in which the driving device has the following members: a pinion which is provided to be integrally rotatable with the spool, a cylinder whose longitudinal direction is provided parallel to a predetermined radial direction of the pinion, a piston slidably accommodated in the cylinder, a rack which is provided at the piston and which, when the piston slides in the cylinder, rotates the pinion in a direction of taking-up the webbing for tensing while meshing with the pinion, and a gas supplying device communicating with the cylinder and supplying gas to the cylinder at a time of rapid deceleration of the vehicle so as to make the piston slide. In addition, the cylinder, and a mounting hole which communicates with the cylinder and which is for mounting the gas supplying device, may be formed in the base member such that central lines in axial directions of the cylinder and the mounting hole are positioned in a plane which is orthogonal to an axial direction of the spool.
In such a pretensioner device, at the time of a rapid deceleration of the vehicle, the gas supplying device operates and supplies gas to the cylinder. The piston slides within the cylinder due to the gas pressure of the gas, and rotates the pinion in the direction of taking-up the webbing for tensing while the rack, which is provided at the piston, meshes with the pinion. In this way, the spool, which is integrally rotatable with the pinion, rotates and takes-up the webbing for tensing, and the webbing for restraining a vehicle occupant is tensed in the direction of restraining the vehicle occupant.
Here, the cylinder and the gas supplying device (mounting hole), which respectively form the driving device, are disposed so as to communicate with one another and such that the central lines in the axial directions thereof are positioned in a plane which is orthogonal to the axial direction of the spool. Therefore, the dimension of the driving device in the widthwise direction (the axial direction of the spool) is small. Namely, the entire pretensioner device can be made even more compact.
In particular, if the cylinder and the gas supplying device (mounting hole) are disposed in directions intersecting one another, the longitudinal dimension of the driving device also can be made smaller.
Further, when the cylinder and the mounting hole are formed in the base member, the number of parts can be reduced. In this way, the assemblability of the pretensioner device is improved and the cost thereof can be reduced.
In the pretensioner device of the present invention described until now, the base member may be mounted between a pair of leg pieces which are provided at a frame for fixing the retractor to the vehicle and which oppose one another so as to substantially correspond to the width of the webbing for restraining a vehicle occupant, such that the widthwise direction of the base member coincides with the direction in which the pair of leg pieces oppose one another.
In such a pretensioner device, due to the spool being able to take-up the webbing for tensing which has a narrower width than the webbing for restraining a vehicle occupant, the base member, which accommodates the spool and the driving device within the widthwise direction dimension of the base member, is mounted (fixed) between the pair of leg pieces of the frame which substantially correspond to the width of the webbing for restraining the vehicle occupant, such that the widthwise direction of the base member coincides with the direction in which the pair of leg pieces oppose one another.
In other words, the pretensioner device is assembled integrally with the retractor. In this way, it suffices to mount the pretensioner device integrally with the retractor to the vehicle, and the mountability of the pretensioner device to the vehicle improves.
In order to achieve the above second object, a seat belt device relating to a second aspect of the present invention is a three-point seat belt device for restraining a vehicle occupant, and comprises a retractor having a take-up shaft which is rotatably supported at a frame fixed to a vehicle body, and at which one end portion of a webbing for restraining a vehicle occupant is anchored, and on which the webbing for restraining a vehicle occupant can be taken-up and from which the webbing for restraining a vehicle occupant can be pulled out, and a pretensioner mechanism which rotates the take-up shaft in a webbing take-up direction at a time of rapid deceleration of a vehicle; and the above-described pretensioner device which is provided at another end portion of the webbing for restraining a vehicle occupant.
The seat belt device of the present invention is a three-point seat belt device in which one end portion of the webbing for restraining a vehicle occupant is anchored to the take-up shaft of the retractor, and the other end portion of the webbing is connected (fixed) to the pretensioner device of the first aspect. Thus, usually, the spool of the pretensioner device fixes and holds, via the webbing for tensing, the other end portion of the webbing for restraining a vehicle occupant which is freely pulled out and taken up by the take-up shaft of the retractor.
When the vehicle occupant is to apply the webbing to himself/herself, for example, in a seat belt device which is applied to the driver""s seat of a vehicle, the vehicle occupant anchors, in the buckle device, the tongue plate disposed at the intermediate portion of the webbing which is trained around and folded over at a through-anchor at the upper portion of the center pillar of the vehicle. In this state, the portion of the webbing for restraining a vehicle occupant, which is from the through-anchor to the tongue plate (i.e., the shoulder webbing), restrains the upper body of the vehicle occupant. The portion of the webbing for restraining a vehicle occupant, which is from the tongue plate to the pretensioner device (i.e., to the webbing for tensing) (i.e., the lap webbing), restrains the waist portion of the vehicle occupant.
In a structure in which, in the initial state, the webbing for tensing is wound on the spool, or in a structure in which the retractor permits pulling-out of the webbing for restraining a vehicle occupant after the pretensioner mechanism is operated, it is preferable to provide a restricting device which restricts rotation of the spool in the direction of pulling-out the webbing for tensing.
When the vehicle rapidly decelerates, the pretensioner mechanism of the retractor and the pretensioner device (the driving device) are both operated. Thus, the pretensioner mechanism rotates the take-up shaft in the webbing take-up direction, and mainly the shoulder webbing is tensed in the direction of restraining the vehicle occupant. Further, the driving device of the pretensioner device rotates the spool in the direction of taking-up the webbing for tensing such that the webbing for tensing is taken up onto the spool, and mainly the lap webbing is tensed in the direction of restraining the vehicle occupant.
In this way, when the vehicle rapidly decelerates, the webbing for restraining a vehicle occupant is tensed from the both end sides thereof so as to appropriately limit the amount of movement of the vehicle occupant, and the vehicle occupant is properly protected. In other words, the ability to restrain the vehicle occupant is good.
Here, the seat belt device is provided with the pretensioner device which is compact as described above. Thus, the seat belt device can on the whole be made more compact, and the space for mounting the seat belt device into a vehicle can be reduced. Moreover, as described above, because there is no need to mount the pretensioner device to the floor panel of a vehicle, there are few effects on the body structure.
When the seat belt device is equipped with the pretensioner device in which the base member is mounted between the pair of leg pieces in accordance with the aforementioned condition, the retractor and the pretensioner device are assembled integrally. Therefore, the retractor and the pretensioner device can be integrally mounted to a vehicle. The mountability of the seat belt device to a vehicle is improved.
In this way, the seat belt device of the present invention is equipped with the above-described pretensioner device, and the space for mounting the seat belt device to a vehicle can be reduced while the ability of the seat belt device to restrain a vehicle occupant is maintained.